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Yep, another developer enthusiastically proposing mmap as an "easy win" for database design, when in reality it often causes hard-to-debug correctness and performance problems.

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To be fair, I use it to share financial time series between multiple processes and as long as there is a single writer it works well. Been in production since several years.

Creating a shared memory buffer by mapping it as a file is not the same as mapping files on disk. The latter has weird and subtle problems, whereas the former just works.

To be clear, I am indeed doing mmap to the same file on disk. Not using shmap. But there is only one thread in one process writing to it and the readers are tolerant to millisecond delays.

> millisecond delays

I thought you said financial time series!

But yeah, this is a case where mmap works great - convenience, not super fast, single writer and not necessarily super durable.

> I thought you said financial time series!

Yeah it is just your average normal financial time series.

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